Cysteine rich proteins for heavy metal decontamination of waste water from oil and gas industries

Abstract

Waste water streams from an oil or gas recovery or refinery operation contaminated with a metal such as a heavy metal (e.g. mercury) can be treated with a protein including chordin and chordin-like proteins so that ion bonding the protein with the metal occurs to give a metal protein complex. The metal protein complex is then removed from the aqueous stream by a process such as flocculation and/or filtration.

What is claimed is: 
     
         1 . A method for reducing concentration of at least one metal in an aqueous steam, the method comprising:
 contacting an aqueous stream contaminated with the at least one metal with at least one protein selected from the group consisting of chordin, chordin-like proteins, and combinations thereof, where:
 the chordin-like protein is a protein that contains a chordin domain of 60-80 amino acids in length and is characterized by at least ten cysteine residues; and 
 the at least one protein is present in an amount effective to ion bond with the at least one metal; 
   ion bonding the protein with the at least one metal producing a metal protein complex; and   removing the metal protein complex from the aqueous stream.   
     
     
         2 . The method of  claim 1 , where the effective amount of the at least one protein to the at least one metal ranges from about a 1:1 mole ratio to about a 10:1 mole ratio. 
     
     
         3 . The method of  claim 1  where the chordin-like proteins are selected from the group consisting of Sog, chordin-like protein 1, chordin-like protein 2, Procollagen IIA, CTGF, Crossveinless-2, Kielin, Kielin/chordin-like protein, and combinations thereof. 
     
     
         4 . The method of  claim 1  where contacting the aqueous stream with the at least one protein comprises introducing the at least one protein into the aqueous stream without live bacteria that produce it. 
     
     
         5 . The method of  claim 5  where the at least one protein is selected from the group consisting of recombinant proteins, synthetic proteins, and combinations thereof. 
     
     
         6 . The method of  claim 1  where contacting the aqueous stream contaminated with the at least one metal with the at least one protein and ion bonding the protein with the metal to give a metal protein complex occur at a temperature in the range of from about 20 to about 50° C. 
     
     
         7 . The method of  claim 1  where the at least one metal is a heavy metal. 
     
     
         8 . The method of  claim 7  where the heavy metal is mercury. 
     
     
         9 . The method of  claim 1  where removing metal protein complex from the aqueous stream is accomplished by a process selected from the group consisting of flocculation, filtration, and combinations thereof. 
     
     
         10 . The method of  claim 1  where the aqueous stream is a waste water stream from an oil or gas recovery or refinery operation. 
     
     
         11 . A method for reducing concentration of at least one heavy metal in an aqueous steam, the method comprising:
 contacting an aqueous stream contaminated with the at least one heavy metal with at least one protein selected from the group consisting of chordin, chordin-like proteins, and combinations thereof, where:
 the chordin-like protein is a protein that contains a chordin domain of 60-80 amino acids in length and is characterized by at least ten cysteine residues; and 
 the protein is present in a mole ratio of at least one protein to at least one heavy metal of about a 1:1 mole ratio to about a 10:1 mole effective to ion bond with the at least one heavy metal; 
   ion bonding the at least one protein with the at least one heavy metal producing a metal protein complex; and   removing the metal protein complex from the aqueous stream.   
     
     
         12 . The method of  claim 11  where contacting the aqueous stream contaminated with a metal with the at least one protein and ion bonding the protein with the metal to give a metal protein complex occur at a temperature in the range of from about 20 to about 50° C. 
     
     
         13 . The method of  claim 11  where the heavy metal is mercury. 
     
     
         14 . The method of  claim 11  where removing metal protein complex from the aqueous stream is accomplished by a process selected from the group consisting of flocculation, filtration, and combinations thereof. 
     
     
         15 . A treated aqueous composition comprising:
 an aqueous stream comprising at least one heavy metal contaminant; and   at least one protein selected from the group consisting of chordin, chordin-like proteins, and combinations thereof, where
 the chordin-like protein is a protein that contains a chordin domain of 60-80 amino acids in length and characterized by at least ten cysteine residues, and 
 the protein is present in an amount effective to ion bond with the at least one heavy metal contaminant. 
   
     
     
         16 . The treated aqueous composition of  claim 15  where the aqueous stream is a waste water stream from an oil or gas recovery or refinery operation 
     
     
         17 . The treated aqueous composition of  claim 15  where the effective amount of the at least one protein to at least one heavy metal contaminant ranges from about a 1:1 mole ratio to about a 10:1 mole ratio. 
     
     
         18 . The treated aqueous composition of  claim 15  where the chordin-like proteins are selected from the group consisting of Sog, chordin-like protein 1, chordin-like protein 2, Procollagen IIA, CTGF, Crossveinless-2, Kielin, Kielin/chordin-like protein, and combinations thereof. 
     
     
         19 . The treated aqueous composition of  claim 15  where concentration of live bacteria that produces the at least one protein is below detection levels. 
     
     
         20 . The treated aqueous composition of  claim 15  where the at least one heavy metal contaminant is mercury.